Structural and optical properties of nanostructured Cr doped CdO thin films for photovoltaic devices

Cr doped CdO thin films were deposited on mica substrates by reactive DC magnetron sputtering technique by varying substrate temperature from room temperature (RT) to 350 °C. X-ray diffraction studies reveal that the films exhibit cubic structure with highly oriented in the (200) direction. The surface morphology of the films was observed by field emission scanning electron microscopy. The optical transmittance of the films increased from 70 to 82% with the increase of substrate temperature. The electrical resistivity of the films was measured by four-probe method. The film deposited at the substrate temperature of 350 °C shows the highest optical transmittance of 82% and is attributed to less scattering effects, structural homogeneity, and better crystallinity. The optical constants (n and k) and optical band gap (Eg) of the films were determined from the optical transmission spectra.